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The common English name of dolphin causes much confusion. This fish is not related to the marine mammals also known as dolphins (family Delphinidae). Additionally, two species of dolphinfish exist, the common dolphinfish (Coryphaena hippurus) and the pompano dolphin (Coryphaena equiselis). Both these species are commonly marketed by their Pacific name, mahi-mahi.

In the Pacific and along the English speaking coast of South Africa they are also commonly called by the Spanish name, Dorado[citation needed]. In the Mediterranean island of Malta, this fish is referred to as the lampuka.[6]

Linnaeus named the genus, derived from the Greek word, κορυφή, koryphe, meaning top or apex, in 1758. Synonyms for the species include Coryphaena argyrurus, Coryphaena chrysurus and Coryphaena dolfyn.[3]

Mahi-mahi can live up to 5 years, although they seldom exceed four. Catches average 7 to 13 kilograms (15 to 29 lb). They seldom exceed 15 kilograms (33 lb), and mahi-mahi over 18 kilograms (40 lb) are exceptional.

Mahi-mahi have compressed bodies and a single long-based dorsal fin extending from the head almost to the tail.[7] Their caudal fins and anal fins are sharply concave. They are distinguished by dazzling colors: golden on the sides, and bright blues and greens on the sides and back. Mature males have prominent foreheads protruding well above the body proper. Females have a rounded head. Females are also usually smaller than males.

The pectoral fins of the mahi-mahi are iridescent blue. The flank is broad and golden. 3 black diagonal stripes appear on each side of the fish as it swiftly darts after prey.

Out of the water, the fish often change color (giving rise to their Spanish name, dorado, "golden"), going though several hues before finally fading to a muted yellow-grey upon death.

Mahi-mahi are among the fastest-growing fish. They spawn in warm ocean currents throughout much of the year, and their young are commonly found in seaweed. Mahi-mahi are carnivorous, feeding on flying fish, crabs, squid, mackerel, and other forage fish. They have also been known to eat zooplankton and crustaceans.

Males and females are sexually mature in their first year, usually by 4–5 months old. Spawning can occur at body lengths of 20 cm. Females may spawn two to three times per year, and produce between 80,000 and 1,000,000 eggs per event.

In waters averaging 28 °C/83 °F, mahi-mahi larvae are found year-round, with greater numbers detected in spring and fall. In one study, seventy percent of the youngest larvae collected in the northern Gulf of Mexico were found at a depth greater than 180 meters. Spawning occurs normally in captivity, with 100,000 eggs per event. Problems maintaining salinity, food of adequate nutritional value and proper size, and dissolved oxygen are responsible for larval mortality rates of 20-40%. [8] Mahi-mahi fish are mostly found in the surface water. Juveniles feed on shrimp, fish and crabs found in rafts of Sargassum weeds. Their flesh is soft and oily, similar to sardines. The body is slightly slender and long, making them fast swimmers; they can swim as fast as 50 knots (92.6 km/h, 57.5 mph).[9]

Mahi-mahi are highly sought for sport fishing and commercial purposes. Sport fishermen seek them due to their beauty, size, food quality, and healthy population. Mahi-mahi is popular in many restaurants.

Fishing charters most often look for floating debris and frigatebirds near the edge of the reef in about 120 feet (37 m) of water. Mahi-mahi (and many other fish) often swim near debris such as floating wood, palm trees and fronds, or sargasso weed lines and around fish buoys. Sargasso is floating seaweed that sometimes holds a complete ecosystem from microscopic creatures to seahorses and baitfish. Frigatebirds dive for food accompanying the debris or sargasso. Experienced fishing guides can tell what species are likely around the debris by the birds' behavior.

Thirty- to fifty-pound gear is more than adequate when trolling for mahi-mahi. Fly-casters may especially seek frigatebirds to find big mahi-mahis, and then use a bait-and-switch technique. Ballyhoo or a net full of live sardines tossed into the water can excite the mahi-mahis into a feeding frenzy. Hookless teaser lures can have the same effect. After tossing the teasers or live chum, fishermen throw the fly to the feeding mahi-mahi. Once on a line, mahi-mahi are fast, flashy and acrobatic, with beautiful blue, yellow, green and even red dots of color.

The United States and the Caribbean countries are the primary consumers of this fish, but many European countries are increasing their consumption every year.[citation needed] It is a popular eating fish in Australia, usually caught and sold as a by-product by tuna and swordfish commercial fishing operators. Japan and Hawaii are significant consumers. The Arabian Sea, particularly the coast of Oman, also has mahi-mahi. At first, mahi-mahi were mostly bycatch (incidental catch) in the tuna and swordfish longline fishery. Now they are sought by commercial fishermen on their own merits.

In French Polynesia, fishermen use harpoons, using a specifically designed boat, the poti marara, to pursue it, because mahi-mahi do not dive. The poti marara is a powerful motorized V-shaped boat, optimized for high agility and speed, and driven with a stick so the pilot can hold his harpoon with his right hand.

Depending on how it is caught, mahi-mahi is classed differently by various sustainability rating systems. It is also a potential vector of toxic microorganisms.

The Monterey Bay Aquarium classifies mahi-mahi, when caught in the US Atlantic, as a Best Choice, the top of its three environmental impact categories. The Aquarium advises to avoid imported mahi-mahi harvested by long line but rates troll and pole-and-line caught as a Good Alternative.

The Environmental Defense Fund (EDF) classifies mahi-mahi caught by line/pole in the US as "Eco-Best" in its three-category system,[11] but classifies all mahi-mahi caught by longline as only "Eco-OK" or "Eco-Worst" due to longline "high levels [of] bycatch, injuring or killing seabirds, sea turtles and sharks."[12]